Some bone marrow biopsy needles are used to obtain bone marrow samples for diagnostic purposes as well as for harvesting marrow for transplant purposes. Such biopsy needles generally include a cannula member having a stainless steel cannula with a hub or handle connected to the proximal end of the cannula, and a stylet member having a stainless steel stylet and a handle or cap connected to the proximal end of the stylet. The cannula is provided with a sharp distal end and receives the stylet which is provided with a sharp pointed distal end that extends distally beyond the distal end of the cannula when the cannula and stylet members are assembled together for penetrating body tissue and bone in order to enter a bone marrow cavity, for example, the iliac crest of the patient. Both handles are hand grasped and considerable pressures are applied to cause the distal ends of the cannula and stylet to penetrate the tissue and bone.
Aspiration of a bone marrow sample is accomplished by removing the stylet member from the cannula member while the distal end of the cannula is in the marrow cavity. Then a syringe is connected to the proximal end of the cannula and marrow fluid is aspirated into the syringe. The aspirated sample is then processed for clinical testing. Where harvesting of marrow, such as for a transplant is desired, a relatively large number of biopsy needle insertions and marrow aspirations are generally required in order to accumulate a suitable amount of marrow. Where a biopsy core sample is to be obtained, the distal ends of the cannula and stylet are inserted into the marrow cavity and, after the stylet is removed, the cannula handle is rotated back and forth while applying axial pressure to the cannula to move the cannula through the marrow and collect a sample core within the cannula. The cannula is then carefully removed from the patient and the core sample pushed through the cannula and out the proximal end, such as by employing a probe. Aspirated samples and core samples may be taken from the same patient for a more complete diagnosis.
Good manual control of the biopsy device during insertion into the bone is necessary in order to avoid inadvertent damage to the patient. The size and shape of the upper portion of the biopsy device that is grasped by the hand of the practitioner, both with and without the stylet member in place, is an important consideration in providing good control of the device during use. Some biopsy devices have had handle portions which tend to concentrate the reaction forces during insertion to relatively small areas of the hand. This tends to produce discomfort or even damage to the practitioner and less control of the biopsy device because of the relatively high pressures applied to the device. This is especially the case where a considerable amount of bone marrow must be collected, such as in the case of a transplant, and a relatively large number of biopsies are required.
Some biopsy devices have employed a ball-type handle which engages a relatively small middle portion of the palm of the hand or a handle having protuberances which tend to concentrate the reaction force to relatively small areas of the palm. Some such devices, in general, have been uncomfortable to the practitioner especially where repeated samples are made. In some cases, when the stylet member was removed from the cannula member, the remaining handle of the cannula member had such a shape or had protuberances which produced discomfort to the practitioner.
Some such biopsy devices had handle locking constructions which produced undesirable protuberances which contacted the hand in use or constructions which could not readily use a luer lock connector for connecting the cannula to a syringe tip luer lock for aspiration of bone marrow fluid.